Christmas Bird Count history report system

# - - - - -   c l a s s   S t a t C e l l

class StatCell(Cell):
    '''Used for mean and standard deviation displays.

      Exports:
        StatCell(value):
          [ value is a float or None ->
              return a new StatCell with that value ]
        .value:      [ as passed to constructor ]
    '''
    __slots__ = ('value')